The white tiger is a recessive mutant of the Bengal tiger, which was reported in the wild from time to time in Assam, Bengal, Bihar and especially from the former State of Rewa. Compared to normal colored tigers without the white gene, white tigers tend to be somewhat bigger than original tigers, both at birth and as fully grown big adults. Kailash Sankhala, the director of the New Delhi Zoo in the 1960s, said “one of the functions of the white gene may have been to keep a size gene in the population, in case it’s ever needed.” Dark-striped white individuals are well-documented in the Bengal Tiger subspecies, also known as the Royal Bengal or Indian tiger (Panthera tigris tigris or P. t. bengalensis), and may also have occurred in captive Siberian Tigers (Panthera tigris altaica), as well as having been reported historically in several other subspecies.